This invention relates to a method of producing a carbon film on a substrate and, more particularly, to a carbon film producing method utilizing a reactive sputtering process for releasing carbon particles from a graphite target electrode to deposite a carbon film on a substrate.
It is the conventional practice to produce carbon films in diamond or amorphous formation on substrates by utilizing an ion beam method or a plasma CVD method. According to such an ion beam method, carbon films are produced by ionizing a carbon source in a vacuum, accelerating the resulting ions in an electrostatic manner, and bombarding a target substrate with the accelerated ions. Therefore, the ion beam method requires a large-sized ion accelerator and has a tendency to produce structural failures in the carbon layer caused by bombardment with ion beams on the substrate. In addition, the ion beam method is not applicable for organic substrates, semiconductive substrates or other materials which would be damaged by bombardment with ion beams. The plasma CVD method utilizes a plasma to decompose hydrocarbon gas (carbon source) into carbon atomic particles. However, in the plasma CVD method there is a tendency for re-polymerization to occur causing production of various kinds of growth nuclide. Therefore, it is very difficult to produce carbon films having desired characteristics. In addition, the plasma CVD method requires the substrate temperature to be maintained above 200.degree. C. Therefore, this method is not applicable to substrates which cannot tolerate such high temperatures.